Admittedly, I'm not too familiar with the series - but having had this go on the Games With Gold list earlier this month - went ahead and picked it up. It now appears it was all in good planning on the part of MS, especially since it's been announced Forza Horizon and all its DLC are reaching their EOL - "End Of Life" status this October 20th.

While we’re reveling in the euphoria of launching a brand-new Forza game, I do have an important update regarding the original Forza Horizon. On October 20, the original Forza Horizon for Xbox 360 will reach “End of Life” status. That means that the game and its associated DLC will no longer be available for purchase. Players who own Forza Horizon before that date will still be able to download and play the game and its associated content as normal. After that date, however, Forza Horizon and its associated DLC will no longer be for sale.